As is known in the concrete pouring business, various types of pins are generally employed in the fixing of the form board. For the small, independent construction contractor who only occasionally does concrete work, a wooden pin is generally made--of 5/4 lumber and whittled to a point, for example--for driving into the ground in setting the board. While sometimes adequate to do the job, pins of this type are not often used (and, because it takes some time and labor to point the lumber, and because it is quite difficult to drive the pin the required depth into the ground to fix the form board, especially where there is an extensive amount of clay and shale present).
A concrete contractor working in the business, on the other hand, utilizes a pin made of steel, with holes drilled through at random intervals, to be driven into the ground next to the form board, and to receive nails hammered through the holes and into the board. While being made of steel--and therefore easier to drive into clay, shale, and other hard surfaces--, such pins are fairly expensive (e.g. priced at some $2.65 for a 16 in. pin of 3/4 in. diameter, and with a 24 in. pin costing that much more). Experience has shown that it is not uncommon for a concrete contractor to purchase 200 or so pins of this type at any one time, packaged 10 to a box; and it then becomes quite annoying, as well as quite costly, to find such pins being lost, or rendered unusable when the holes begin to fill with overpoured concrete and allowed to set--each as a result of shoddy workmanship at the jobsite. Because dirt is continually being knocked about at the job location, because the steel form pins are of a color similar to that of the dirt, and because the colorization of the concrete is not that very much different from that of the pins, the construction worker frequently forgets to retrieve the pins after the nails have been pulled from the form board when the concrete has set. What with the chaos of the ongoing pour, it is not unusual for the worker to forget the pin, leaving it behind--or to forget to clean out the concrete which accumulates in the holes of the pin.
Experience has further shown that while the typical concrete construction worker does not view the retrieval of these form pins for later use as a priority item, such matter represents a major concern in the concrete pouring business, being one of an unnecessary recurring expense.